This invention relates to a radar signal simulator and is applicable to the simulation of radar signals from imaginary objects which may be stationary or moving. These imaginary objects may be emitters or reflectors of radiation. Radar signal simulators are needed for testing radar equipment and for training purposes. Heretofore, simulated radar signals have not looked very realistic when displayed on the radar screen.
Efforts have been made in the past to attenuate the amplitude of simulated radar signals so as to reproduce the effects which in a real signal would arise from a horizontal polar diagram of an antenna. One such system is described in U.S. Pat. No. 3,108,274 which describes apparatus in which a circular plate intersects a waveguide carrying a microwave signal. The plate has a crescent-shaped aperture which allows a varying amplitude of signal to pass along the waveguide thereby simulating signals received by a radar antenna when scanning a target.
In another system, described in U.S. Pat. No. 3,792,475 an attempt is made to reproduce the varying intensity of radiation received when the latter is being scanned by a search radar. Neither of these systems deals with the problems of simulating signals received by a three dimensional radar, simulating signals received from moving targets or distinguishing between signals received from sources of radiation, eg jammers, and signals which are echoes from non-emitting targets.